How to know if a part sees a certain object?
Is there a specific way to do it instead of making a new part where, when it's touched some code will fire? I'm making it so that an NPC will react if the player is seen by it.
1 answer
Yes, you should check out raycasting to do this:
http://wiki.roblox.com/index.php/Raycasting
http://wiki.roblox.com/index.php?title=API:Class/Workspace/FindPartOnRay
http://wiki.roblox.com/index.php?title=API:Class/Workspace/FindPartOnRayWithIgnoreList
This tutorial can also help you as an example:
http://wiki.roblox.com/index.php?title=Making_a_ray-casting_laser_gun
Try casting a ray from the NPC to the player (as an optimization, consider only casting the ray if the players are not too far away to be seen in the first place).
Consider using the dot product to test if the player is behind the NPC, since unless they are aliens they probably can't see behind them: http://wiki.roblox.com/index.php?title=Dot_product